The invention relates to a turbine rotor blade arrangement and a method for the provision of sealing air in a turbine rotor blade arrangement.
It is known to cool the turbine rotor blades of a gas turbine. For cooling the turbine rotor blades, the turbine rotor blades have internal cooling air channels that are impinged with air that is supplied via a disc channel in the turbine disc. At that, the disc channels end at the blade root reception areas of the turbine disc that receive the blade roots of the turbine rotor blades. Here, a portion of air that exits from a disc channel is discharged as leakage flow through a gap formed between the blade root and the blade root reception area and extending in the axial direction. The air that escapes through the gap as a leakage flow is referred to as sealing air, since a driving pressure ratio is present across the gap, and the air can be used for sealing. The air that exits from a disc channel is thus referred to as cooling air if it serves for cooling purposes, and is referred to as sealing air if it exits as a leakage flow, wherein sealing air can generally also be used for cooling different components.
In the event of unfavorable operational conditions or structural component tolerances, there is the danger of the driving pressure ratio being reduced across the gap between the blade root and the blade root reception area and leading to a reversal of the leakage flow. Since this leakage flow also represents a part of the sealing air sealing against the hot air from the main flow channel of the gas turbine, which has very high temperatures directly behind the combustion chamber, there is the danger of such hot air flowing in front of the turbine disc, and further entering the turbine rotor blade via the mentioned gap and damaging the disc.
U.S. Pat. No. 4,505,640 A describes is a turbine rotor blade arrangement in which the gap that is formed between the blade root and the blade root reception area is sealed by means of a seal to minimize the leakage flow.
There is a need to provide a turbine rotor blade arrangement and a method for providing sealing air which reliably protect air channels formed in the blade root or between the blade root and the blade root reception area against hot air.